Internal combustion engines may utilize direct fuel injection, wherein fuel is directly injected in to an engine cylinder, to improve fuel gas mixing. In traditional direct fuel injectors, the injector nozzle hole configuration and geometry can regulate combustion characteristics and effect vehicle emissions. The fuel is typically injected from a sac at the tip of the fuel injector needle into the engine cylinder through a plurality of holes, configured in various forms to increase atomization and improve air-fuel mixing.
One example approach for improving air-fuel mixing with a direct injector is shown by Abani et al. in WO2014052126. Therein, an injector nozzle comprises a plurality of holes skewed with respect to the axis of the injector in order to impart an angular momentum on a plume of injected fuel.
However, the inventors herein have recognized some issues with the above fuel injector. For example, because the fuel is ejected out of the nozzle at high pressure, the fuel may have a relatively long spray penetration, despite the swirl imparted by the skewed nozzle holes. As a result, the fuel may impinge upon the cylinder walls. Particularly during cold engine conditions, the fuel on the cylinder wall may not participate in combustion, leading to fueling errors and compromising emissions. Further, the fuel flow may be difficult to accurately control during relatively short injection durations, such as during pre- or post-injection events.
Thus, a fuel injector system is presented herein to at least partly address the above issues. In one example, the fuel injector system comprises a needle, a plurality of tangential tins coupled to a nozzle end of the needle, an actuator coupled to the needle, and a controller storing non-transitory instructions that when executed cause the controller to, responsive to a command to inject fuel, activate the actuator to push the needle in a downward direction by an amount based on one or more operating parameters. In this way, the fuel may travel over the nozzle end when the fuel is injected out of the injector, atomizing the fuel to promote mixing and imparting rotational momentum to the fuel spray. Further, the amount the needle is actuated (e.g., the downward distance the needle travels during the injection event) may be controlled based on operating conditions, such as desired fuel injection quantity and/or engine temperature, to accurately meter relatively small amounts of fuel while controlling the spray penetration of the injected fuel.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.